Pneumatic and equalized mechanical spring suspension for half axles



Oct. 10, 1961 F. K. H. NALLINGER PNEUMATIC AND EQUALIZED MECHANICALSPRING SUSPENSION FOR HALF AXLES Flled March 25 1958 3,963,575 PatentedOct. 19, 19ml has 3,003,575 PNEUMATIC AND EQUALKZED MECHANKCALSPRINGSUSPENSION FQR HALF AXLES Friedrich K. H. Nallinger, Stuttgart-N,Germany, as-

signor to Daimler-Benz Aktiengesellschaft, Stuttgarh Unterturkheim,Germany Filed Mar. 25, 1958, Ser. No. 723,827 Claims priority,application Germany Mar. 39, 1957 1 Claim. (Cl.180-73) My inventionrelates to an improved spring system for vehicles, more particularlymotor vehicles, and it is its primary object to improve the ridingqualities of the vehicle by the provision of pneumatic springs and toreduce the dimensions of such pneumatic springs by relieving them ofpart of the load of the vehicle. Viewed from another aspect of myinvention, it is the object thereof to provide an effective springsystem which is simple and reliable in operation, lends itself tomanufacture at a low cost and imparts superior riding qualities to thevehicle.

Further objects of my invention Will appear from a detailed descriptionof a preferred embodiment thereof following hereinafter with referenceto the drawings. I wish it to be understood, however, that my inventionis in no way limited to the details of such embodiment but is capable ofnumerous modifications within the scope of the appended claims and thatthe terms and phrases used in such detailed description have been chosenfor the purpose of illustrating the invention rather than that ofrestricting or limiting same.

In the drawing I have shown a rear view of a motor vehicle chassisshowing the driven rear wheels thereof and the improved spring systemassociated therewith, the tires of the wheels being shown in section.

The frame that may be an integral part of the body of the vehicleincludes a transverse beam 1 and a bracket 2 fixed thereto and dependingfrom the central portion thereof. The lower end of this bracket carriescoaxial pivotal bearings for a pair of half axles d and mounted foroscillation about an axis 3 extending fore and aft. The half axle 5 isrigidly connected with a housing 6 encasing the rear axle transmissionincluding the differential gears. Hence, both the half axle 5 and thecasing 6 will swing about the axis 3 in unison. An arm 7 is fixed to thehalf axle 4 and extends upwardly therefrom. Similarly, an arm 8 is fixedto the half axle 5 and extends upwardly therefrom. A helical spring 9 isprovided to connect the arms 7 and 8. More particularly, these armsextend upwardly, generally peipendicular to the respective axles, andthe helical spring is a pressure spring held in compression between thearms above the housing 6 and the pivotal axis 3 and extending generallyhorizontally or parallel to the axles 4 and 5.

On the outside of the arms 7 and 8 pneumatic springs for-med by bellowsill and 11 are interposed between the half axles 4 and 5 and springsupports fixed to the ends of the transverse beam 1. These bellows reston the half axles and, for this purpose, the latter may be provided withspring seats 14 for the bellows which may be inwardly inclined, asshown.

Moreover, shock absorbers of the telescope type are interposed betweenthe frame 1 and the half axles 4 and 5 and are pivotally connectedthereto. Wheels W are rotatably mounted on the ends of the half axles 4and 5.

From the foregoing it will appear that the pair of opposite wheels W aremounted for upand-down movement relative to the frame by the bracket 2and the half axles 4 and 5. The pneumatic springs formed by the bellowsand 11 are individually associated with the wheels W, each pneumaticspring being responsive to its associated wheel only Therefore,up-and-down movement of one wheel will not affect the bellows associatedwith the other wheel. The additional flexible springing meansconstituted by the helical spring 9, however, is associated with both ofthe wheels through the intermediary of the half axles and is exclusivelyresponsive to the geometric sum of the movements of both wheels. Thiswill readily appear from a consideration of what happens when one wheelmoves upwardly and the other Wheel moves downwardly the same distancethus reducing the geometric sum of the movements of both wheels to zero.In this event the half axles will swing about the axis 3 in the sameangular direction through the same angle holding their arms 7 and 8 inunchanged spaced relationship. As a consequence, the spring '9 will beneither expanded nor compressed or, in other words, will not respond tothe movements of the wheels.

If one of the wheels, however, for instance the wheel W carried by thehalf axle 4, moves upwardly when rolling over an obstruction, the arm 7will compress the spring 9. At the same time the air will be compressedin the bellows it As a result, the reactionary force exerted by the roadsurface upon the wheel W will be transferred to the frame by both, thepneumatic spring 10 and the flexible spring 9, the latter enabling thehalf axles and 5 to exert an upwardly directed force upon the bracket 2supporting part of the weight of the vehicle.

The spring system described has numerous advantages. This will bereadily understood from a consideration of the efiect of the pneumaticbellows. If the entire load to be carried by one of the wheels W wouldbe transferred by a single pneumatic spring, same would require verylarge dimensions. My improved spring system, however, makes it possibleto considerably reduce the dimensions of the pneumatic spring as eachwheel is sprung by both, the pneumatic spring and the mechanical spring9. The pneumatic spring, however, has a particularly favorable springcharacteristic because of the progressive effect thereof. The additionalmechanical spring Q is utilized at the same time to obtain an equalizingeffect between the two wheels. Hence, the mechanical spring has the dualfunction of serving as an additional spring permitting it to reduce thedimensions of the pneumatic spring and to equalize the spring forces,thereby improving the riding qualities of the vehicle.

The improved effect of my novel spring system may be also understood bya consideration of the effect of the equalizing spring 9. Any equalizingspring requires the provision of an additional stabilizer spring. In theabsence of such stabilizer spring interposed between the wheels and theframe of the vehicle, no restoring couple would be exerted upon theframe or body of the vehicle. This restoring couple must be effected byadditional stabilizer springs. In my improved system such stabilizersprings are formed by the pneumatic springs having a progressive springcharacteristic and being, therefore, particularly effective in rapidlyreturning the body to its central position of equilibrium. Nevertheless,the pneumatic springs have a very soft spring characteristic for mediumloads.

It is a feature of particular utility of the embodiment shown that theaxis 3 is common to both of the half axles. This has the effect ofresulting in smaller angular displacements of the arms 7 and it thanobtainable with half axles having spaced pivotal axes disposed on bothsides of the vertical central longitudinal plane of the vehicle.

While the invention has been described in connection with a preferredembodiment thereof, it will be understood that it is capable of furthermodification, and this application is intended to cover any variations,uses, or adaptations of the invention following, in general, theprinciples of the invention and including such departures from thepresent disclosure as come within known or customary practice in the artto which the invention pertains, and as fall within the scope of theinvention or the limits of the appended claim.

What I claim is:

In a motor vehicle, the combination comprising frame means, said framemeans including a transverse beam member, a pair of half axles, meansfor pivotally supporting said half axles on said transverse beam memberfor oscillation individually about only one axis extending essentiallyfore and aft, resilient connecting means between said transverse beammember and said half axles comprising two pneumatic spring bellows, oneeach of said two bellows being respectively associated with a respectiveone of said half axles, said transverse beam member terminating inseating means for one end of each said bellows, said seating means beingoutwardly and downwardly inclined relative to said transverse beammember, each of said half axles comprising seating means for the otherend of each of said bellows, said lastnamed seating means facingupwardly and being inclined angularly to the axis of a respective halfaxle, the bellows of one half axle being operative independently of thebellows of the other half axle and providing each a progressive Springcharacteristic in response to oscillation of the respective half axle,one spring abutment for each half axle, each spring abutment beingsecured to a respective half axle for oscillating movement therewith,and a mechanical spring responsive exclusively to the geometric sum ofthe movements of the half axles and operatively connected between saidspring abutments to serve simultaneously as equalizing spring and asauxiliary spring to aid said two pneumatic spring bellows in case ofspring movements of said half axles producing a resultant geometric sum,shock absorbers having lower ends connected to said half axlesintermediate said seating means on said half axles and having upper endsconnected to said transverse beam member intermediate said seating meanson said transverse beam member, said lower ends being spaced apart agreater distance than the distance between said upper ends, and a rearaxle transmission housing between said half axles, said mechanicalspring being a compression spring and disposed above said housing.

References Cited in the file of this patent UNITED STATES PATENTS2,105,369 Paton Jan. 11, 1938 2,257,913 Maranville Oct. 7, 19412,419,104 Wilfert Apr. 15, 1947 2,818,128 Uhlenhaut Dec. 31, 19572,934,352 Polhemus Apr. 26, 1960 FOREIGN PATENTS 704,270 Great BritainFeb. 17,1954 178,394 Switzerland Sept. 16, 1935

